The present invention relates to the field of encapsulation and, more particularly, to methods for encapsulating active agents with an inorganic coating.
The art of encapsulation has developed various processes and methods for individually coating particulate matter for purposes of controlled release or metering out of an active agent over a prolonged period. However, heretofore, such processes have invariably been based upon the use of organic polymers of nonpolymeric organic materials such as fats and waxes as the coating material. Typical prior art processes are described, for example, in U.S. Pat. Nos. 2,800,457, 2,800,458, 3,041,289, 3,341,466, 3,415,758, 3,429,827, 3,594,327, 3,639,256 and 3,674,704. Such complex organic coating materials may be of unknown metabolic fate and therefore not compatible with the environment for applications such as encapsulation of pesticides and insecticidal agents. It would be useful, therefore, to have available an encapsulation system and technique which provides an inexpensive means of producing capsules which are compatible with the environment and which provide effective activity for a prolonged period.